Orthostatic lavage solutions or colon evacuants for cleansing the gastrointestinal tract were introduced into medical practice only within the last five years. The available solutions which seek to produce volumogenic diarrhoea by ingestion of relatively large volumes of electrolyte solution are almost all identical in their contents of salts, formulated so that they are relatively isotonic, and include poorly absorbable polyethylene glycol. Solutions which are commonly employed include 0.9% sodium chloride, balanced electrolyte solutions, lactated Ringers, mannitol and polyethylene glycol containing electrolyte solutions.
These solutions induce copious diarrhoea when the volume of the solution is greater than the bowel's capacity to distend and absorb it. Generally about 4 to 5 litre of the solution is necessary to obtain adequate cleansing of the gastrointestinal tract for colonoscopy or bowel surgery. Apart from the necessary diarrhoeagenic effect the large volume required and the particularly unpleasant taste of the solutions contribute to the chief side effects of nausea and vomiting. These side effects are counter productive in reaching the desired aim of complete and rapid purging and cleansing of the bowel. The unpalatability of the solutions also result in poor patient compliance.
Flavouring the currently used solution with standard agents is difficult due to the large destabilizing amount of flavouring agents required to block the unpleasant nauseating taste of salts. Sugar based flavours are not acceptable since delivery of unabsorbed sugars to the colon provides a substrate for bacteria to elaborate explosive gases such as hydrogen and methane. In fact, recent studies (J. Crowe et al..sup.1) have indicated that even the unflavoured polyethylene glycol solutions currently in use may create hydrogen and methane in potentially explosive concentrations when cautery is used within the colon.
Furthermore, most bowel preparations using orthostatic lavage precede either colonoscopy or bowel surgery with a lesser usage in barium-enema bowel radiology. Since patients requiring such procedures are usually in the older age group and may be candidates for surgery after discovery of a bowel cancer, for example, it would be of advantage if the solution had bacteriocidal properties and/or could simultaneously replace nutrients necessary for repair.
Therefore it would be desirable to provide a colon evacuant wherein the unpleasant taste of the normally used isotonic solutions containing PEG is masked, wherein it has endogenous diarrhoea producing properties, and wherein it confers bacteriostatic of bacteriocidal properties to reduce bowel gas production or post-operative infection and yet can replace some nutrient value pre-operatively.
It is an object of the present invention to provide an agent which may be combined with flavouring and sweetening agents, which significantly reduces the potential for explosion due to a reduction of explosive gasses secondary to a bacteriostatic effect on bowel bacteria, and which allows a reduction in the volume of standard lavage solutions containing polyethylene glycol by at least about 25%.
Thus providing a more palatable and effective formulation, with fewer side effects, greater patient compliance and less risk of explosion.